1. Field of the Invention
The present invention relates to an organic light emitting device, and more particularly, to an organic light emitting device including an inorganic layer and a hole transport layer, which is free from exciton quenching by preventing diffusion of impurities derived from a hole injection layer into an emitting layer, and has a high emission efficiency and an extended lifetime by improvements in electron blocking and backward diffusion phenomenon and hole transport capability into the emitting layer.
2. Description of the Related Art
Organic light emitting devices are self-emissive displays that emit light by recombination of electrons and holes in a fluorescent or phosphorescent organic layer when an electrical current is applied to the organic layer. The organic light emitting devices have advantages such as lightweight, simple constitutional elements, easy fabrication process, superior image quality, and wide viewing angle. In addition, the organic light emitting devices perfectly create moving pictures, produce high color purity, and have electrical properties suitable for portable electronic equipment such as low power consumption and low driving voltage.
In the organic light emitting devices, a multi-layer structure composed of a hole injection layer, an emitting layer, an electron injection layer, etc. is generally used as an organic layer, instead of a single emitting layer, in view of enhancement in emission efficiency and decrease in driving voltage.
As an example of an organic light emitting device with such a multi-layer structure, U.S. Pat. No. 6,670,053, by Conley et al., discloses an organic light emitting device including a layer made of a 3-phenylindolyl group-containing organic compound between a hole transport layer and an emitting layer. Meanwhile, U.S. Pat. No. 6,603,150, by Liao et al., discloses an organic light emitting device including an interface layer made of an organic material between a hole transport layer and an emitting layer to provide more balanced carrier recombination.
However, common organic light emitting devices provide unsatisfactory emission efficiency and lifetime. Therefore, there is a strong need for the improvement of organic light emitting devices.